Sometime the name of the microorganisms and the microbial diseases are derived from the place of first isolation of the organism or occurrence of the disease. Sometime these names create confusion because the organism or disease initially confined in particular location, now may be prevalent all over the world.
In this blog post, I have compiled a list of some such diseases and their etiological agents. I hope you will enjoy this blog post, please do let forget to share with friends and leave a comment if there is something important you want to share with me.
- California Encephalitis virus: California encephalitis virus, a member of the bunyavirus family, was first isolated from mosquitoes in California in 1952, but its name is something of a misnomer because most human disease occurs in the north-central states of USA. The strain of the California Encephalitis virus that causes encephalitis most frequently is called La Crosse (for the city of Wisconsin where it was first isolated).
La Crosse virus is the most common arboviral cause of encephalitis in the United States of America. It is transmitted by the mosquito Aedes.
- Colorado Tick Fever Virus (CTF): Colorado tick fever is a reovirus transmitted by the wood tick among the small rodents eg, Chipmunks and Squirrrels, of the Rocky Mountains. There are approximately 100-300 cases per year in the United States of America.
This disease occurs primarily in people hiking or camping in the Rocky Moutains and is characterized by fever, headache, retro-orbital pain, and severe myalgia. Diagnosis is done by virus isolation (from blood) or by detecting the rise in antibody titre. No antiviral therapy or vaccine is available. Prevention involves wearing protective clothing and inspecting the skin for ticks.
- Eastern Equine encephalitis virus: It is a member of togavirus family. It causes Encephalitis along the east coast of the United States of America. Encephalitis is severe but uncommon. This virus is transmitted to humans by mosquitoes from small wild birds, such as sparrow. There is no antiviral therapy and non vaccine for humans.
- Ebola Virus:Ebola virus a member of filovirus family is named for the river in Zaire that was the site of outbreak of hemorrhagic fever in 1976. The mortality rate associated with Ebola virus is nearly 100%. Ebola virus causes shock, gastrointestinal bleeding disseminated intravascular coagulation. Severe thrombocytopenia causes hemorrhages. Most of the cases arise by secondary transmission from contact with the patient’s blood or secretions. Natural host of this virus is unknown. Diagnosis of Ebola viral disease is made by isolating the virus or by detecting rise in antibody titre.
- Human African trypanosomiasis (HAT), or African sleeping sickness
Japanese Encephalitis Virus: It is the most common cause of epidemic encephalitis. The disease is most prevalent in South East Asia. Japanese Encephalitis virus is a member of the flavivirus family. It is transmitted to human by certain species of Culex mosquitoes endemic to Asian rice fields. Disease diagnosis can be done by isolating virus, detecting IgM antibody in serum or spinal fluid, or by staining brain tissue with fluorescent antibody. There is no antiviral therapy.
Lassa Fever Virus: This virus was first seen in Lassa town of Nigeria in 1969. Lassa fever virus is the member of arenavirus family. It causes a severe, often fatal hemorrhagic fever, death occurs by vascular collapse.The virus is transmitted to humans by contamination of food or water with animal urine. Small rodent called Mastomys is the natural host for Lassa fever virus. Ribavirin if given early reduces mortality rate. No vaccine is available.
Marburg Virus: It is the member of the filovirus family. It causes hemorrhagic fever with a mortality rate of nearly 100%. Marburg virus was first recognized as a cause of human disease in 1967 in Marburg, Germany. Natural reservoir of Marburg Virus is still unknown. In 2005, Marburg virus outbreaks killed hundreds of people in Angola. Isolation of virus or detection in rise in antibody titre is used as diagnostic tools. No antiviral therapy and vaccine is available.
- Rift Valley Fever:
- Rive Blindness: Caused by Onchocerca volvulus
- Rocky Mountain Spotted Fever:
- St. Louis Encephalitis virus:St. Louis Encephalitis Virus is found in the southern, central and western states and causes 10-30 cases of encephalitis per year in the United States. St. Louis Encephalitis Virus is transmitted by several species of Culex mosquitoes. Small wild birds esp English sparrow are the reservoir and humans are the dead end hosts.In contrast of Eastern Equine Encephalitis Virus and Western Equine Encephalitis virus which are predominantly rural, St. Louis Encephalitis virus occurs in urban areas (because of the preference of these mosquitoes to breed in stagnant water)
- Swimming pool granuloma: Caused by Mycobacterium marinum
- Western Equine Encephalitis virus: It causes less severe illness and 5-20 cases of Western Equine Encephalitis virus occurs every year in USA with a mortality rate of 20%. This virus is transmitted primarily by Culex mosquitoes among wild-bird population of the western states, especially in areas with irrigated farmland. No antiviral therapy for human is available. Diagnosis is made by isolating virus or observing rise in antibody titre.
- West Nile Virus (WNV): West Nile Virus is a flavivirus that is classified in the same antigenic group as St. Louis Encephalitis Virus. It is endemic in Africa but has caused encephalitis in areas of Europe and Asia as well. Wild animals are main reservoirs of this virus, which is transmitted mainly by culex mosquitoes.